Memory device

ABSTRACT

A memory device is provided. The memory device includes a plurality of memory cells arranged in a matrix of a plurality of rows and a plurality of columns. A first column of the plurality of columns of the matrix includes a first plurality of memory cells of the plurality of memory cells, a first pair of bit lines connected to each of the first plurality of bit cells, and a second pair of bit lines connectable to the first pair of bit lines through a plurality of switches.

BACKGROUND

A common type of integrated circuit memory is a static random accessmemory (SRAM) device. An SRAM device includes an array of memory cells.Each memory cell uses a predetermined number of transistors connectedbetween an upper reference potential and a lower reference potentialsuch that one of two storage nodes are occupied by the information to bestored, with the complementary information stored at the other storagenode. In one example, an SRAM memory cell arrangement includes sixtransistors. Each bit in the SRAM cell is stored on four of the sixtransistors, which transistors form cross-coupled inverters. Theremaining two transistors are connected to a word line which controlsaccess to the memory cell during read and write operations byselectively connecting the memory cell to bit lines.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a diagram of an example memory device, in accordance with someembodiments.

FIG. 2 is a diagram of an example memory device illustrating an examplecell array, in accordance with some embodiments.

FIG. 3 is a diagram of an example memory device illustrating an exampleinput/output circuit, in accordance with some embodiments.

FIG. 4 is a diagram of an example memory device illustrating an examplenegative voltage generator circuit, in accordance with some embodiments.

FIG. 5 is a diagram illustrating an example memory device with exampleequalizer switches, in accordance with some embodiments.

FIG. 6 is a diagram of another example memory device, in accordance withsome embodiments.

FIG. 7 is a diagram illustrating an example memory device with a dualport cell, in accordance with some embodiments.

FIG. 8 is a flow diagram illustrating an example method for operating amemory device, in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In accordance with some disclosed examples, a memory device with anadditional pair of bit lines is provided. More specifically, a staticrandom access memory (SRAM) device with additional bit line pairs toimprove a performance of the SRAM device during write operations isprovided. The additional bit line pairs are selectively connectable toexisting bit line pairs for the write operation. This, as explained inthe following sections of the disclosure, increases the performance ofthe memory device for the write operation. In some embodiments, theadditional bit line pairs are formed in a different metal layer thanthat of the existing bit line pairs. For example, the additional bitline pairs are formed in a higher metal layer than that of the existingbit line pairs. That is, if the existing bit line pairs are formed inmetal layer 1 then the additional bit line pairs are formed in metallayer 2 or above.

FIG. 1 is a diagram illustrating an example memory device 100 inaccordance with some embodiments. As shown in FIG. 1, memory device 100includes a word line driver circuit 102, a cell array 104, a multiplexer106, and a write driver circuit 108. However, it will be apparent to aperson with the ordinary skill in the art after reading this disclosurethat memory device 100 can include additional components not shown inFIG. 1. For example, memory device 100 can include a pre-charge circuit,a read select circuit, a write select circuit, etc.

Cell array 104 includes a plurality of cells (also referred to as bitcells or memory cells) arranged in a matrix of rows and columns. Each ofthe plurality of memory cells are operative to store one bit ofinformation (that is, a bit value 0 or a bit value 1). In addition, cellarray 104 includes a plurality of word lines, a plurality of bit linepairs, and a plurality of additional bit line pairs (not shown). Eachcell of cell array 104 is connected to a word line and a bit line pairfor a read operation and a word line, a bit line pair, and an additionalbit line pair for a write operation.

Word line driver circuit 102 is operative to select a word line of cellarray 104 and charge the selected word line to a logic high for a readoperation or a write operation. In example embodiments, word line drivercircuit 120 is a decoder circuit which includes a plurality of logicoperators to decode potentials on address lines to select a word line tocharge. The address lines are charged to a logic high (that is,approximately equal to a first predefined potential) or a logic low(that is, approximately equal to a second predefined potential). Thefirst predefined potential is approximately equal to a supply voltage(that is, VDD). The second predetermined potential is approximatelyequal to the ground voltage or zero volts. However, other suitable logiclow and logic high voltages may be employed. A logic high is representedby bit value 1 and a logic low is represented by bit value 0.

Multiplexer 106 is operative to select a column of cell array 104 andpre-charge a bit line pair associated with the selected column to apredetermined voltage for a read operation. In addition, multiplexer 106is operative to select a column of cell array 104 and pre-charge both abit line pair and an additional bit line pair associated with theselected column to a predetermined voltage for a write operation. Writedriver circuit 108 is operative to write one bit of information to oneor more bit cells connected to the selected one of the plurality of wordlines and the selected bit line pair of the plurality of bit line pairs.

FIG. 2 is a diagram of example memory device 100 illustrating cell array104 in greater detail in accordance with some embodiments. As shown inFIG. 2, cell array 104 includes a plurality of cells, for example, cell202[0][n−1], . . . , cell 202[m-1][n−1], cell 202[m][n−1], . . . , cell202[2m−1][n−1], cell 202[0][n], . . . , cell 202[m−1][n], cell202[m][n], . . . , and cell 202[2m−1][n]. An example cell of theplurality of cells includes a pair of cross-coupled invertors (alsoreferred to as Q and Q-bar, where Q-bar is complementary to Q) to storethe one bit of information. The cross coupled inverters are connected topair of access transistors which grant access to the information storedin the cross-coupled invertors. In example embodiments, the plurality ofcells of cell array 104 are formed using four transistors, sixtransistors, or eight transistors. In addition, the plurality of cellsof cell array 104 are a single port cell or a multi-port (such as, adual port and a three port) cell.

The plurality of cells are arranged in a matrix of a plurality ofcolumns and a plurality of rows. For example, a first plurality of cellslabeled as 202[0][n−1], 202[m−1][n−1], 202[m][n−1], 202[2m−1][n−1] arearranged in a [n−1]th column 204. In addition, another first pluralityof cells labeled as 202[0][n], 202[m−1][n], 202[m][n], 202[2m−1][n] arearranged in a [n]th column 206. Although, cell array 104 is shown toinclude only two columns, that is, [n−1]th column 204 and [n]th column206, it will be apparent to a person with an ordinary skill in the artafter reading this disclosure that cell array 104 may include adifferent number of columns. For example, cell array 104 can include 32,64, 128, 256, 512, or 1024 columns.

Continuing with FIG. 2, a second plurality of cells labeled as202[0][n−1] and 202[0][n] are arranged in a [0]th row. In addition,another second plurality of cells labeled as 202[m−1][n−1] and202[m−1][n] are arranged in [m−1]th row. Similarly, yet another secondplurality of cells labeled as 202[m][n−1] and 202[m][n] are arranged in[m]th row continuing to yet another second plurality of cells labeled as202[2m−1][n−1] and 202[2m−1][n] which are arranged in a [2m−1]th row ofcell array 104. It will be apparent to a person with ordinary skill inthe art after reading this disclosure that cell array 104 includes apredetermined number of rows. For example, cell array 104 may include32, 64, 128, 256, 512, or 1024 rows.

Each cell of a row of the plurality of rows is connected to a word lineWL. For example, and as shown in FIG. 2, cell 202[0][n−1] and cell202[0][n] of [0]th row are connected to a [0]th word line WL[0] 216[0].In addition, cell 202[m−1][n−1] and cell 202[m−1][n] of [m−1]th row areconnected to a [m−1]th word line WL[m−1] 216[m−1]. Similarly, cell202[m][n−1] and cell 202[m][n] of [m]th row are connected to a [m]thword line WL[m] 216[m] continuing to cell 202[2m−1][n−1]0 and cell202[2m−1][n] of [2m−1]th row which are connected to a [2m−1]th word lineWL[2m−1] 216[m−1].

Moreover, each cell of a column of the plurality of columns is connectedto a bit line pair (that is, a bit line and a complementary bit line,also referred to as a lower bit line LBL and a lower bit line bar LBLBrespectively). For example, the first plurality of cells of [n−1]thcolumn 204 are associated with and connectable to an [n−1]th bit linepair. That is, first plurality of cells labeled as 202[0][n−1],202[m−1][n−1], 202[m][n−1], 202[2m−1][n−1] arranged in [n−1]th column204 are associated with and connectable to a [n−1]th bit line LBL[n−1]208 a[n−1] and a [n−1]th complementary bit line LBLB[n−1] 208 b[n−1].Similarly, the first plurality of cells of [n]th column 206 areassociated with and connectable to an [n]th bit line pair. That is,another first plurality cells labeled as 202[0][n], 202[m−1][n],202[m][n], 202[2m−1][n] and arranged in [n]th column 206 are associatedwith and connectable to [n]th bit line LBL[n] 208 a[n] and a [n]thcomplementary bit line LBLB[n] 208 b[n].

In addition, and shown in FIG. 2, each bit line pair of cell array 104is associated with and is connectable to an additional bit line pair(that is, an additional bit line and an additional complementary bitline, also referred to as a higher bit line HBL and a higher bit linebar HBLB respectively). For example, [n−1]th bit line pair is associatedwith and is connectable to [n−1]th additional bit line pair. Morespecifically, a [n−1]th bit line LBL[n−1] 208 a[n−1] of [n−1]th bit linepair is associated with connectable to a [n−1]th additional bit lineHBL[n−1] 210 a[n−1] of [n−1]th additional bit line pair. Similarly, a[n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of [n−1]th bit linepair is associated with and connectable to a [n−1]th additionalcomplementary bit line HBLB[n−1] 210 b[n−1] of [n−1]th additional bitline pair.

Moreover, [n]th bit line pair is associated with and is connectable[n]th additional bit line pair. More specifically, a [n]th bit lineLBL[n] 208 a[n] of [n]th bit line pair is associated with andconnectable to a [n]th additional bit line HBL[n] 210 a[n] of [n]thadditional bit line pair. Similarly, a [n]th complementary bit lineLBLB[n] 208 b[n] of [n]th bit line pair is associated with andconnectable to a [n]th additional complementary bit line HBLB[n] 210b[n] of [n]th additional bit line pair.

In example embodiments, [n−1]th bit line LBL[n−1] 208 a[n−1] of [n−1]thbit line pair is connectable to [n−1]th additional bit line HBL[n−1] 210a[n−1] of [n−1]th additional bit line pair through a plurality of[n−1]th switches. In other embodiments, [n−1]th bit line LBL[n−1] 208a[n−1] of [n−1]th bit line pair is connectable to [n−1]th additional bitline HBL[n−1] 210 a[n−1] of [n−1]th additional bit line pair through aswitch after every m rows, where m is predetermined. For example,[n−1]th bit line LBL[n−1] 208 a[n−1]of [n−1]th bit line pair isconnectable to [n−1]th additional bit line HBL[n−1] 210 a[n−1] of[n−1]th additional bit line pair through a [n−1]th first switch 212 a0[n−1] after first m rows (that is, after row numbers [0] to [m−1]) andthrough a [n−1]th second switch 212 a 1[n−1] after next m rows (that is,after row numbers [m] to [2m−1]). In example embodiments, m rowsincludes between 16 rows and 256 rows. [n−1]th bit line LBL[n−1] 208a[n−1] of [n−1]th bit line pair is connected to [n−1]th additional bitline HBL[n−1] 210 a[n−1] of [n−1]th additional bit line pair when one ormore of the plurality of [n−1]th switches are switched ON. For example,[n−1]th bit line LBL[n−1] 208 a[n−1] of [n−1]th bit line pair isconnected to [n−1]th additional bit line HBL[n−1] 210 a[n−1] of [n−1]thadditional bit line pair when one or both of [n−1]th first switch 212 a0[n−1] and [n−1]th second switch 212 a 1[n−1] are switched ON. Byextension, [n−1]th bit line LBL[n−1] 208 a[n−1] of [n−1]th bit line pairis disconnected from [n−1]th additional bit line HBL[n−1] 210 a[n−1] of[n−1]th additional bit line pair when both of [n−1]th first switch 212 a0[n−1] and [n−1]th second switch 212 a 1[n−1] are switched OFF.

In example embodiments, each of [n−1]th first switch 212 a 0[n−1] and[n−1]th second switch 212 a 1[n−1] is a n-channel metal oxidesemiconductor (nMOS) transistor. However, other types transistors, forexample, a metal oxide semiconductor field effect transistor (MOSFET), ap-channel metal oxide semiconductor (pMOS) transistor, a complementarymetal oxide semiconductor (CMOS) transistor, etc., are within the scopeof the disclosure. A source of each of [n−1]th first switch 212 a 0[n−1]and [n−1]th second switch 212 a 1[n−1] is connected to [n−1]th bit lineLBL[n−1] 208 a[n−1] and a drain of each of [n−1]th first switch 212 a0[n−1] and [n−1]th second switch 212 a 1[n−1] is connected to [n−1]thadditional bit line HBL[n−1] 210 a[n−1]. However, each of [n−1]th firstswitch 212 a 0[n−1] and [n−1]th second switch 212 a 1[n−1] issymmetrical. Hence, a source of each of [n−1]th first switch 212 a0[n−1] and [n−1]th second switch 212 a 1[n−1] can be a drain and a draincan be a source.

Similarly, [n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of[n−1]th bit line pair is connectable to [n−1]th additional complementarybit line HBLB[n−1] 210 b[n−1] of [n−1]th additional bit line pairthrough a plurality of [n−1]th complementary switches. In exampleembodiments, [n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of[n−1]th bit line pair is connectable to [n−1]th additional complementarybit line HBLB[n−1] 210 b[n−1] of [n−1]th additional bit line pairthrough a switch after every m rows, where m is predetermined. Forexample, [n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of [n−1]thbit line pair is connectable to [n−1]th additional complementary bitline HBLB[n−1] 210 b[n−1] of [n−1]th additional bit line pair through[n−1]th first complementary switch 212 b 0[n−1] after first m rows (thatis, after row number [0] to [m−1]) and through [n−1]th secondcomplementary switch 212 b 1[n−1] after next m rows (that is, after rownumbers [m] to [2m−1]). In example embodiments, m rows includes between16 rows and 256 rows.

[n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of [n−1]th bit linepair is connected to [n−1]th additional complementary bit line HBLB[n−1]210 b[n−1] of [n−1]th additional bit line pair when one or more of theplurality of [n−1]th complementary switches are switched ON. Forexample, [n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of [n−1]thbit line pair is connected to [n−1]th additional complementary bit lineHBLB[n−1] 210 b[n−1] of [n−1]th additional bit line pair when one orboth of [n−1]th first complementary switch 212 b 0[n−1] and [n−1]thsecond complementary switch 212 b 1[n−1] are switched ON. By extension,[n−1]th complementary bit line LBLB[n−1] 208 b[n−1] of [n−1]th bit linepair is disconnected from [n−1]th additional complementary bit lineHBLB[n−1] 210 b[n−1] of [n−1]th additional bit line pair when both of[n−1]th first complementary switch 212 b 0[n−1] and [n−1]th secondcomplementary switch 212 b 1[n−1] are switched OFF.

In example embodiments, each of [n−1]th first complementary switch 212 b0[n-1] and [n−1]th second complementary switch 212 b 1[n−1] is an-channel metal oxide semiconductor (nMOS) transistor. However, othertypes of transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. A source ofeach of [n−1]th first complementary switch 212 b 0[n−1] and [n−1]thsecond complementary switch 212 b 1[n−1] is connected to [n−1]thcomplementary bit line LBLB[n−1] 208 b[n−1] and a drain of each of[n−1]th first complementary switch 212 b 0[n−1] and [n−1]th secondcomplementary switch 212 b 1[n−1] is connected to [n−1]th additionalcomplementary bit line HBLB[n−1] 210 b[n−1]. However, each of [n−1]thfirst complementary switch 212 b 0[n−1] and [n−1]th second complementaryswitch 212 b 1[n−1] is symmetrical. Hence, a source of each of [n−1]thfirst complementary switch 212 b 0[n−1] and [n−1]th second complementaryswitch 212 b 1[n−1] can be a drain and a drain can be a source.

In addition, [n]th bit line of [n]th bit line pair is connectable to[n]th additional bit line of [n]th additional bit line pair through aplurality of [n]th switches. In example embodiments, [n]th bit lineLBL[n] 208 a[n] of [n]th bit line pair is connectable to [n]thadditional bit line HBL[n] 210 a[n] of [n]th additional bit line pairthrough a switch after every m rows, where m is predetermined. Forexample, [n]th bit line LBL[n] 208 a[n] of [n]th bit line pair isconnectable to [n]th additional bit line HBL[n] 210 a[n] of [n]thadditional bit line pair through a [n]th first switch 212 a 0[n] afterfirst m rows (that is, after row numbers [0] to [m−1]) and through a[n]th second switch 212 a 1[n] after second m rows (that is, after rownumbers [m] to [2 m−1]). In example embodiments, m rows includes between16 rows and 256 rows.

[n]th bit line LBL[n] 208 a[n] of [n]th bit line pair is connected to[n]th additional bit line HBL[n] 210 a[n] of [n]th additional bit linepair when one or more of the plurality of [n]th switches are switchedON. For example, [n]th bit line LBL[n] 208 a[n] of [n]th bit line pairis connected to [n]th additional bit line HBL[n] 210 a[n] of [n]thadditional bit line pair when one or both of [n]th first switch 212 a0[n] and [n]th second switch 212 a 1[n] are switched ON. By extension,[n]th bit line LBL[n] 208 a[n] of [n]th bit line pair is disconnectedfrom [n]th additional bit line HBL[n] 210 a[n] of [n]th additional bitline pair when both of [n]th first switch 212 a 0[n] and [n]th secondswitch 212 a 1[n] are switched OFF.

In example embodiments, each of [n]th first switch 212 a 0[n] and [n]thsecond switch 212 a 1[n] is a n-channel metal oxide semiconductor (nMOS)transistor. However, other types of transistors, for example, a MOSFET,a pMOS transistor, a CMOS transistor, etc., are within the scope of thedisclosure. A source of each of [n]th first switch 212 a 0[n] and [n]thsecond switch 212 a 1[n] is connected to [n]th bit line LBL[n] 208 a[n]and a drain of each of [n]th first switch 212 a 0[n] and [n]th secondswitch 212 a 1[n] is connected to [n]th additional bit line HBL[n] 210a[n]. However, each of [n]th first switch 212 a 0[n] and [n]th secondswitch 212 a 1[n] is symmetrical. Hence, a source of each of [n]th firstswitch 212 a 0[n] and [n]th second switch 212 a 1[n] can be a drain anda drain can be a source.

Moreover, [n]th complementary bit line LBLB[n] 208 b[n] of [n]th bitline pair is connectable to [n]th additional complementary bit lineHBLB[n] 210 b[n] of [n]th additional bit line pair through a pluralityof complementary switches. In example embodiments, [n]th complementarybit line LBLB[n] 208 b[n] of [n]th bit line pair is connectable to [n]thadditional complementary bit line HBLB[n] 210 b[n] of [n]th additionalbit line pair through a switch after every [m]th row, where m ispredetermined. For example, [n]th complementary bit line LBLB[n] 208b[n] of [n]th bit line pair is connectable to [n]th additionalcomplementary bit line HBLB[n] 210 b[n] of [n]th additional bit linepair through [n]th first complementary switch 212 b 0[n] after first mrows (that is, after row number [0] to [m−1]) and through [n]th secondcomplementary switch 212 a 1[n−1] after second m rows (that is, afterrow number [m] to [2m−1]). In example embodiments, m rows includesbetween 16 rows and 256 rows.

[n]th complementary bit line LBLB[n] 208 b[n] of [n]th bit line pair isconnected to [n]th additional complementary bit line HBLB[n] 210 b[n] of[n]th additional bit line pair when one or more of the plurality of[n]th complementary switches are switched ON. For example, [n]thcomplementary bit line LBLB[n] 208 b[n] of [n]th bit line pair isconnected to [n]th additional complementary bit line HBLB[n] 210 b[n] of[n]th additional bit line pair when one or both of [n]th firstcomplementary switch 212 b 0[n] and [n]th second complementary switch212 b 1[n] are switched ON. By extension, [n]th complementary bit lineLBLB[n] 208 b[n] of [n]th bit line pair is disconnected from [n]thadditional complementary bit line HBLB[n] 210 b[n] of [n]th additionalbit line pair when both of [n]th first complementary switch 212 b 0[n]and [n]th second complementary switch 212 b 1[n] are switched OFF.

In example embodiments, each of [n]th first complementary switch 212 b0[n] and [n]th second complementary switch 212 b 1[n] is a n-channelmetal oxide semiconductor (nMOS) transistor. However, other types oftransistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. A source ofeach of [n]th first complementary switch 212 b 0[n] and [n]th secondcomplementary switch 212 b 1[n] is connected to [n]th complementary bitline LBLB[n] 208 b[n] and a drain of each of [n]th first complementaryswitch 212 b 0[n] and [n]th second complementary switch 212 b 1[n] isconnected to [n]th additional complementary bit line HBLB[n] 210 b[n].However, each of [n]th first complementary switch 212 b 0[n] and [n]thsecond complementary switch 212 b 1[n] is symmetrical. Hence, a sourceof each of [n]th first complementary switch 212 b 0[n] and [n]th secondcomplementary switch 212 b 1[n] can be a drain and a drain can be asource.

Gates of each of the switches connecting a bit line pair with anadditional bit line pair located in a row are connected to a writeenable line WEL. Hence, the write enable lines WEL can be shared withwhole columns and no column selector circuit is required for selectingwrite enable lines WEL. In addition, the write enable line WEL do notneed an address decoder as they are directly associated with a writeenable signal. For example, gates of each of [n−1]th first switch 212 a0[n−1], [n−1]th first complementary switch 212 b 0[n−1], [n]th firstswitch 212 a 0[n], and [n]th first complementary switch 212 b 0[n] areconnected to a first write enable line WEL[0] 214[0]. Hence, each of[n−1]th first switch 212 a 0[n−1], [n−1]th first complementary switch212 b 0[n−1], [n]th first switch 212 a 0[n], and [n]th firstcomplementary switch 212 b 0[n] are switched ON when first write enableline WEL[0] 214[0] is at a logic high and are switched OFF when firstwrite enable line WEL[0] 214[0] is at a logic low.

In addition, gates of each of [n−1]th second switch 212 a 1[n−1],[n−1]th second complementary switch 212 b 1[n−1], [n]th second switch212 b 1[n], and [n]th second complementary switch 212 b 1[n] areconnected to a second write enable line WEL[1] 214[1]. Hence, each of[n−1]th second switch 212 a 1[n−1], [n−1]th second complementary switch212 b 1[n−1], [n]th second switch 212 a 1[n], and [n]th secondcomplementary switch 212 b 1[n] are switched ON when second write enableline WEL[1] 214[1] is at a logic high and are switched OFF when secondwrite enable line WEL[1] 214[1] is at a logic low.

In example embodiments, first write enable line WEL[0] 214[0] and secondwrite enable line WEL[1] 214[1] are connected to write enable drivercircuit 218. Write enable driver circuit 218 is operative to chargefirst write enable line WEL[0] 214[0] and second write enable lineWEL[1] 214[1] to a logic high for a write operation, thereby connectinga bit line pair with an associated additional bit line pair. Forexample, when first write enable line WEL[0] 214[0] and second writeenable line WEL[1] 214[1] are charged to a logic high, each of [n−1]thfirst switch 212 a 0[n−1] and [n−1]th second switch 212 a 1[n−1] areswitched ON connecting [n−1]th bit line LBL[n−1] 208 a[n−1] with [n−1]thfirst additional bit line HBL[n−1] 210 a[n−1]. In addition, when firstwrite enable line WEL[0] 214[0] and second write enable line WEL[1]214[1] are charged to a logic high, each of [n−1]th first complementaryswitch 212 b 0[n−1] and [n−1]th second complementary switch 212 b 1[n−1]are switched ON connecting [n−1]th complementary bit line LBLB[n−1] 208b[n−1] with [n−1]th first additional complementary bit line HBLB[n−1]210 b[n−1].

In addition, when first write enable line WEL[0] 214[0] and second writeenable line WEL[1] 214[1] are charged to a logic high, each of [n]thfirst switch 212 a 0[n] and [n]th second switch 212 a 1[n] are switchedON connecting [n]th bit line LBL[n] 208 a[n] with [n]th first additionalbit line HBL[n] 210 a[n]. Moreover, when first write enable line WEL[0]214[0] and second write enable line WEL[1] 214[1] are charged to a logichigh, each of [n]th first complementary switch 212 b 0[n] and [n]thsecond complementary switch 212 b 1[n] are switched ON connecting [n]thcomplementary bit line LBLB[n] 208 b[n] with [n]th first additionalcomplementary bit line HBLB[n] 210 b[n].

Connection an additional bit line pair to an existing bit line pair fora write operation reduces an effective bit line resistance for aselected column. Write enable driver circuit 218 is operative to chargefirst write enable line WEL[0] 214[0] and second write enable lineWEL[1] 214[1] to a logic low for a read operation. During a readoperation, the addition bit line pairs are not connected to acorresponding bit line pair.

FIG. 3 is diagram of memory device 100 depicting an example input/output(I/O) circuit 302 in accordance with some embodiments. I/O circuit 302is operative to read data from or write data to cell array 104. As shownin FIG. 3, I/O circuit 302 includes a [n−1]th pre-charge circuit firsttransistor 304 a[n−1] and a [n−1]th pre-charge circuit second transistor304 b[n−1]. In addition, I/O circuit 302 includes a [n−1]th pre-chargecircuit third transistor 306 [n−1]. Both [n−1]th pre-charge circuitfirst transistor 304 a[n−1] and [n−1]th pre-charge circuit secondtransistor 304 b[n−1] are pMOS transistors. However, other types oftransistors, for example, a MOSFET, a nMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,[n−1]th pre-charge circuit third transistor 306 [n−1] is a nMOStransistor. However, other types of transistors, for example, a MOSFET,a pMOS transistor, a CMOS transistor, etc., are within the scope of thedisclosure.

A source of each of [n−1]th pre-charge circuit first transistor 304a[n−1] and [n−1]th pre-charge circuit second transistor 304 b[n−1] isconnected to a supply voltage (that is, VDD). A drain of [n−1]thpre-charge circuit first transistor 304 a[n−1] is connected to a sourceof [n−1]th pre-charge circuit third transistor 306[n−1] which in turn isconnected to [n−1]th bit line LBL[n−1] 208 a[n−1]. A drain of [n−1]thpre-charge circuit second transistor 304 b[n−1] is connected to a drainof [n−1]th pre-charge circuit third transistor 306[n−1] which in turn isconnected to [n−1]th complementary bit line LBLB[n−1] 208 b[n−1].

In example embodiments, each of [n−1]th pre-charge circuit firsttransistor 304 a[n−1], [n−1]th pre-charge circuit second transistor 304b[n−1], and [n−1]th pre-charge circuit third transistor 306[n−1] aresymmetrical. Hence, a source of each of [n−1]th pre-charge circuit firsttransistor 304 a[n−1], [n−1]th pre-charge circuit second transistor 304b[n−1], and [n−1]th pre-charge circuit third transistor 306[n−1] can bea drain, and a drain can be a source. In examples, [n−1]th pre-chargecircuit first transistor 304 a[n−1], [n−1]th pre-charge circuit secondtransistor 304 b[n−1], and [n−1]th pre-charge circuit third transistor306 [n−1] are also referred to as existing transistors.

A gate of [n−1]th pre-charge circuit first transistor 304 a[n−1] isconnected to a gate of [n−1]th pre-charge circuit second transistor 304b[n−1] which in turn is connected to a gate of [n−1]th pre-chargecircuit third transistor 306[n−1]. The gate of [n−1]th pre-chargecircuit third transistor 310[n−1] is also connected to a pre-charge barPCB terminal. In example embodiments, when the pre-charge bar PCBterminal is at a logic low, [n−1]th bit line LBL[n−1] 208 a[n−1] and[n−1]th complementary bit line LBLB[n−1] 208 b[n−1] are pre-charged.However, when the pre-charge bar PCB terminal is at a logic high,[n−1]th bit line LBL[n−1] 208 a[n−1] and [n−1]th complementary bit lineLBLB[n−1] 208 b[n−1] are floating for a read and write operation.[n−1]th bit line LBL[n−1] 208 a[n−1] and [n−1]th complementary bit lineLBLB[n−1] 208 b[n−1] are pre-charged for a read operation or a writeoperation.

Moreover, I/O circuit 302 includes a [n−1]th pre-charge circuit firstadditional transistor 308 a[n−1] and a [n−1]th pre-charge circuit secondadditional transistor 308 b[n−1]. I/O circuit 302 further includes a[n−1]th pre-charge circuit third additional transistor 310 [n−1]. Both[n−1]th pre-charge circuit first additional transistor 308 a[n−1] and[n−1]th pre-charge circuit second additional transistor 30 bb[n−1] arepMOS transistors. However, other types of transistors, for example, aMOSFET, a nMOS transistor, a CMOS transistor, etc., are within the scopeof the disclosure. In addition, [n−1]th pre-charge circuit thirdadditional transistor 310 [n−1] is a nMOS transistor. However, othertypes of transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure.

A source of each of [n−1]th pre-charge circuit first additionaltransistor 308 a[n−1] and [n−1]th pre-charge circuit second additionaltransistor 308 b[n−1] is connected to a supply voltage (that is, VDD). Adrain of [n−1]th pre-charge circuit first additional transistor 308a[n−1] is connected to a source of [n−1]th pre-charge circuit thirdadditional transistor 310[n−1] which in turn is connected to [n−1]thadditional bit line HBL[n−1] 210 a[n−1]. A drain of [n−1]th pre-chargecircuit second additional transistor 308 b[n−1] is connected to a drainof [n−1]th pre-charge circuit third additional transistor 310[n−1] whichin turn is connected to [n−1]th complementary additional bit lineHBLB[n−1] 210 b[n−1].

In example embodiments, each of [n−1]th pre-charge circuit firstadditional transistor 308 a[n−1], [n−1]th pre-charge circuit secondadditional transistor 308 b[n−1], and [n−1]th pre-charge circuit thirdadditional transistor 310[n−1] are symmetrical. Hence, a source of eachof [n−1]th pre-charge circuit first additional transistor 308 a[n−1],[n−1]th pre-charge circuit second additional transistor 308 b[n−1], and[n−1]th pre-charge circuit third additional transistor 310[n−1] can be adrain, and a drain can be a source. In examples, [n−1]th pre-chargecircuit first additional transistor 308 a[n−1], [n−1]th pre-chargecircuit second additional transistor 308 b[n−1], and [n−1]th pre-chargecircuit third additional transistor 310[n−1] are smaller in size than[n−1]th pre-charge circuit first transistor 304 a[n−1], [n−1]thpre-charge circuit second transistor 304 b[n−1], and [n−1]th pre-chargecircuit third transistor 306 [n−1] (that is, the existing transistors).

A gate of [n−1]th pre-charge circuit first additional transistor 308a[n−1] is connected to a gate of [n−1]th pre-charge circuit secondadditional transistor 308 b[n−1] which in turn is connected to a gate of[n−1]th pre-charge circuit third additional transistor 310[n−1]. Thegate of [n−1]th pre-charge circuit third additional transistor 310[n−1]is also connected to the pre-charge bar PCB terminal. In exampleembodiments, when the pre-charge bar PCB terminal is at a logic low,[n−1]th additional bit line HBL[n−1] 210 a[n−1] and [n−1]th additionalcomplementary bit line HBLB[n−1] 210 b[n−1] are pre-charged. However,when the pre-charge bar PCB terminal is at a logic high, [n−1]thadditional bit line HBL[n−1] 210 a[n−1] and [n−1]th additionalcomplementary bit line HBLB[n−1] 210 b[n−1] are floating for a writeoperation. In examples, therefore, [n−1]th additional bit line HBL[n−1]210 a[n−1] and [n−1]th additional complementary bit line HBLB[n−1] 210b[n−1] are pre-charged using an existing pre-charge bar PCB terminal.

Still continuing with FIG. 3, I/O circuit 302 further includes a [n−1]thwrite select circuit first transistor 312 a[n−1] and a [n−1]th writeselect circuit second transistor 312 b[n−1]. A source of [n−1]th writeselect circuit first transistor 312 a[n−1] is connected to [n−1]th bitline LBL[n−1] 208 a[n−1] and a source of [n−1]th write select circuitsecond transistor 312 b[n−1] is connected to [n−1]th complementary bitline LBLB[n−1] 208 b[n−1]. A drain of each of [n−1]th write selectcircuit first transistor 312 a[n−1] and [n−1]th write select circuitsecond transistor 312 b[n−1] is connected to ground.

In example embodiments, each of [n−1]th write select circuit firsttransistor 312 a[n−1] and [n−1]th write select circuit second transistor312 b[n−1] is an nMOS transistor. However, other types of transistors,for example, a MOSFET, a pMOS transistor, a CMOS transistor, etc., arewithin the scope of the disclosure. In addition, each of [n−1]th writeselect circuit first transistor 312 a[n−1] and [n−1]th write selectcircuit second transistor 312 b[n−1] are symmetrical. Hence, a source ofeach of [n−1]th write select circuit first transistor 312 a[n−1] and[n−1]th write select circuit second transistor 312 b[n−1] can be adrain, and a drain can be a source. In examples, [n−1]th write selectcircuit first transistor 312 a[n−1] and [n−1]th write select circuitsecond transistor 312 b[n−1] are also referred to as existingtransistors.

I/O circuit 302 further includes a [n−1]th write select circuit firstadditional transistor 314 a[n−1] and a [n−1]th write select circuitsecond additional transistor 314 b[n−1]. A source of [n−1]th writeselect circuit first transistor 312 a[n−1] is connected to [n−1]thadditional bit line HBL[n−1] 210 a[n−1] and a source of [n−1]th writeselect circuit second additional transistor 314 b[n−1] is connected to[n−1]th complementary additional bit line HBLB[n−1] 210 b[n−1]. A drainof each of [n−1]th write select circuit first additional transistor 314a[n−1] and [n−1]th write select circuit second additional transistor 314b[n−1] is connected to ground. Moreover, a gate of [n−1]th write selectcircuit first transistor 312 a[n−1] is connected to a gate of [n−1]thwrite select circuit first additional transistor 314 a[n−1]. Inaddition, a gate of [n−1]th write select circuit second transistor 312b[n−1] is connected to a gate of [n−1]th write select circuit secondadditional transistor 314 b[n−1].

In example embodiments, each of [n−1]th write select circuit firstadditional transistor 314 a[n−1] and [n−1]th write select circuit secondadditional transistor 314 b[n−1] is a nMOS transistor. However, othertypes of transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,each of [n−1]th write select circuit first additional transistor 314a[n−1] and [n−1]th write select circuit second additional transistor 314b[n−1], are symmetrical. Hence, a source of each of [n−1]th write selectcircuit first additional transistor 314 a[n−1] and [n−1]th write selectcircuit second additional transistor 314 b[n−1] can be a drain, and adrain can be a source. In examples, [n−1]th write select circuit firstadditional transistor 314 a[n−1] and [n−1]th write select circuit secondadditional transistor 314 b[n−1] are smaller in size than [n−1]th writeselect circuit first transistor 312 a[n−1] and [n−1]th write selectcircuit second transistor 312 b[n−1] (that is, the existingtransistors).

I/O circuit 302 further includes a [n−1]th write select first logiccircuit 316 a[n−1] and a [n−1]th write select second logic circuit 316b[n−1]. Each of [n−1]th write select first logic circuit 316 a[n−1] and[n−1]th write select second logic circuit 316 b[n−1] includes a NORlogic gate. However, other types of logic circuits are within the scopeof the disclosure.

A first input terminal of [n−1]th write select first logic circuit 316a[n−1] is connected to data input true (DT) terminal and a second inputterminal of [n−1]th write select first logic circuit 316 a[n−1] isconnected to a [n−1]th write select bit WYB[n−1] terminal. An outputterminal of [n−1]th write select first logic circuit 316 a[n−1] isconnected to a gate of each of [n−1]th write select circuit firsttransistor 312 a[n−1] and [n−1]th write select circuit first additionaltransistor 314 a[n−1].

A first input terminal of [n−1]th write select second logic circuit 316b[n−1] is connected to data input bar (DB) terminal and a second inputterminal of [n−1]th write select second logic circuit 316 b[n−1] isconnected to [n−1]th write select bit WYB[n−1] terminal. An outputterminal of [n−1]th write select second logic circuit 316 b[n−1] isconnected to a gate of each of [n−1]th write select circuit secondtransistor 312 b[n−1] and [n−1]th write select circuit second additionaltransistor 314 b[n−1]. In example embodiments, when the [n−1]th writeselect bit WYB[n−1] is at a logic low, a write operation is selected byboth [n−1]th write select first logic circuit 316 a[n−1] and [n−1]thwrite select second logic circuit 316 b[n−1]. However, when the [n−1]thwrite select bit WYB[n−1] is at a logic high, a write operation is notselected by any of [n−1]th write select first logic circuit 316 a[n−1]and [n−1]th write select second logic circuit 316 b[n−1]. In addition,when the write operation is selected, and when the data input true (DT)terminal is at a logic high, a bit value of 1 is written in cell array104. Moreover, when the write operation is selected, and when the datainput true (DT) terminal is at a logic low, a bit value of 0 is writtenin cell array 104.

I/O circuit 302 further includes a [n−1]th read select circuit firsttransistor 318 a[n−1] and a [n−1]th read select circuit secondtransistor 318 b[n−1]. A source of [n−1]th read select circuit firsttransistor 318 a[n−1] is connected to a drain of [n−1]th pre-chargecircuit first transistor 304 a[n−1] which is connected to [n−1]th bitline LBL[n−1] 208 a[n−1]. Similarly, a source of [n−1]th read selectcircuit second transistor 318 b[n−1] is connected to a drain of [n−1]thpre-charge circuit second transistor 304 b[n−1] which is connected to[n−1]th complementary bit line LBLB[n−1] 208 b[n−1]. A drain of [n−1]thread select circuit first additional transistor 318 a[n−1] is connectedto a data line DL and a drain of [n−1]th read select circuit secondtransistor 318 b[n−1] is connected to a data line bar DLB terminal. Thedata line DL and the data line bar DLB terminal are used for readingdata from cell array 104.

Moreover, a gate of [n−1]th read select circuit first transistor 318a[n−1] is connected to a gate of [n−1]th read select circuit secondtransistor 318 b[n−1] which in turn is connected to a [n−1]th readselect bit RYB[n−1] terminal. In example embodiments, when the [n−1]thread select bit RYB[n−1] is at a logic low, a read operation isselected. However, when the [n−1]th read select bit RYB[n−1] is at alogic high, a read operation is not selected.

In example embodiments, each of [n−1]th read select circuit firsttransistor 318 a[n−1] and [n−1]th read select circuit second transistor318 b[n−1] is a pMOS transistor. However, other types of transistors,for example, a MOSFET, a nMOS transistor, a CMOS transistor, etc., arewithin the scope of the disclosure. In addition, each of [n−1]th readselect circuit first transistor 318 a[n−1] and [n−1]th read selectcircuit second transistor 318 b[n−1], are symmetrical. Hence, a sourceof each of [n−1]th read select circuit first transistor 318 a[n−1] and[n−1]th read select circuit second transistor 318 b[n−1] can be a drain,and a drain can be a source.

Continuing with FIG. 3, I/O circuit 302 further includes a [n]thpre-charge circuit first transistor 304 a[n] and a [n]th pre-chargecircuit second transistor 304 b[n]. In addition, I/O circuit 302includes a [n]th pre-charge circuit third transistor 306 [n]. Both [n]thpre-charge circuit first transistor 304 a[n] and [n]th pre-chargecircuit second transistor 304 b[n] are pMOS transistors. However, othertypes of transistors, for example, a MOSFET, a nMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,[n]th pre-charge circuit third transistor 306 [n] is a nMOS transistor.However, other types of transistors, for example, a MOSFET, a pMOStransistor, a CMOS transistor, etc., are within the scope of thedisclosure.

A source of each of [n]th pre-charge circuit first transistor 304 a[n]and [n]th pre-charge circuit second transistor 304 b[n] is connected toa supply voltage (that is, VDD). A drain of [n]th pre-charge circuitfirst transistor 304 a[n] is connected to a source of [n]th pre-chargecircuit third transistor 306[n] which in turn is connected to [n]th bitline LBL[n] 208 a[n]. A drain of [n]th pre-charge circuit secondtransistor 304 b[n] is connected to a drain of [n]th pre-charge circuitthird transistor 306[n] which in turn is connected to [n]thcomplementary bit line LBLB[n] 208 b[n].

In example embodiments, each of [n]th pre-charge circuit firsttransistor 304 a[n], [n]th pre-charge circuit second transistor 304b[n], and [n]th pre-charge circuit third transistor 306[n] aresymmetrical. Hence, a source of each of [n]th pre-charge circuit firsttransistor 304 a[n], [n]th pre-charge circuit second transistor 304b[n], and [n]th pre-charge circuit third transistor 306[n] can be adrain, and a drain can be a source. In examples, [n]th pre-chargecircuit first transistor 304 a[n], [n]th pre-charge circuit secondtransistor 304 b[n], and [n]th pre-charge circuit third transistor306[n] are also referred to as existing transistors.

A gate of [n]th pre-charge circuit first transistor 304 a[n] isconnected to a gate of [n]th pre-charge circuit second transistor 304b[n] which in turn is connected to a gate of [n]th pre-charge circuitthird transistor 306[n]. The gate of [n]th pre-charge circuit thirdtransistor 310[n] is also connected to a pre-charge bar PCB terminal. Inexample embodiments, when the pre-charge bar PCB terminal is at a logiclow, [n]th bit line LBL[n] 208 a[n] and [n]th complementary bit lineLBLB[n] 208 b[n] are pre-charged. However, when the pre-charge bar PCBterminal is at a logic high, [n]th bit line LBL[n] 208 a[n] and [n]thcomplementary bit line LBLB[n] 208 b[n] are floating for a read andwrite operation. [n]th bit line LBL[n] 208 a[n] and [n]th complementarybit line LBLB[n] 208 b[n] are pre-charged for a read operation or awrite operation.

Moreover, I/O block 302 includes a [n]th pre-charge circuit firstadditional transistor 308 a[n] and a [n]th pre-charge circuit secondadditional transistor 308 b[n]. In addition, I/O block 302 includes a[n]th pre-charge circuit third additional transistor 310[n]. Both [n]thpre-charge circuit first additional transistor 308 a[n] and [n]thpre-charge circuit second additional transistor 30 bb[n] are pMOStransistors. However, other types of transistors, for example, a MOSFET,a pMOS transistor, a CMOS transistor, etc., are within the scope of thedisclosure. In addition, [n]th pre-charge circuit third additionaltransistor 310[n] is a nMOS transistor. However, other types oftransistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure.

A source of each of [n]th pre-charge circuit first additional transistor308 a[n] and [n]th pre-charge circuit second additional transistor 308b[n] is connected to a supply voltage (that is, VDD). A drain of [n]thpre-charge circuit first additional transistor 308 a[n] is connected toa source of [n]th pre-charge circuit third additional transistor 310[n]which in turn is connected to [n]th additional bit line HBL[n] 210 a[n].A drain of [n]th pre-charge circuit second additional transistor 308b[n] is connected to a drain of [n]th pre-charge circuit thirdadditional transistor 310[n] which in turn is connected to [n]thcomplementary additional bit line HBLB[n] 210 b[n].

In example embodiments, each of [n]th pre-charge circuit firstadditional transistor 308 a[n], [n]th pre-charge circuit secondadditional transistor 308 b[n], and [n]th pre-charge circuit thirdadditional transistor 310[n] are symmetrical. Hence, a source of each of[n]th pre-charge circuit first additional transistor 308 a[n], [n]thpre-charge circuit second additional transistor 308 b[n], and [n]thpre-charge circuit third additional transistor 310[n] can be a drain,and a drain can be a source. In examples, [n]th pre-charge circuit firstadditional transistor 308 a[n], [n]th pre-charge circuit secondadditional transistor 308 b[n], and [n]th pre-charge circuit thirdadditional transistor 310[n] are smaller in size than [n]th pre-chargecircuit first transistor 304 a[n], [n]th pre-charge circuit secondtransistor 304 b[n], and [n]th pre-charge circuit third transistor306[n] (that is, the existing transistors).

A gate of [n]th pre-charge circuit first additional transistor 308 a[n]is connected to a gate of [n]th pre-charge circuit second additionaltransistor 308 b[n] which in turn is connected to a gate of [n]thpre-charge circuit third additional transistor 310[n]. The gate of [n]thpre-charge circuit third additional transistor 310[n] is also connectedto the pre-charge bar PCB terminal. In example embodiments, when thepre-charge bar PCB terminal is at a logic low, [n]th additional bit lineHBL[n] 210 a[n] and [n]th additional complementary bit line HBLB[n] 210b[n] are pre-charged. However, when the pre-charge bar PCB terminal isat a logic high, [n]th additional bit line HBL[n] 210 a[n] and [n]thadditional complementary bit line HBLB[n] 210 b[n] are floating for awrite operation. In examples, therefore, [n]th additional bit lineHBL[n] 210 a[n] and [n]th additional complementary bit line HBLB[n] 210b[n] are pre-charged using an existing pre-charge bar PCB terminal.

Still continuing with FIG. 3, I/O circuit 302 further includes a [n]thwrite select circuit first transistor 312 a[n] and a [n]th write selectcircuit second transistor 312 b[n]. A source of [n]th write selectcircuit first transistor 312 a[n] is connected to [n]th bit line LBL[n]208 a[n] and a source of [n]th write select circuit second transistor312 b[n] is connected to [n]th complementary bit line LBLB[n] 208 b[n].A drain of each of [n]th write select circuit first transistor 312 a[n]and [n]th write select circuit second transistor 312 b[n] is connectedto ground.

In example embodiments, each of [n]th write select circuit firsttransistor 312 a[n] and [n]th write select circuit second transistor 312b[n] is an nMOS transistor. However, other types of transistors, forexample, a MOSFET, a pMOS transistor, a CMOS transistor, etc., arewithin the scope of the disclosure. In addition, each of [n]th writeselect circuit first transistor 312 a[n] and [n]th write select circuitsecond transistor 312 b[n] are symmetrical. Hence, a source of each of[n]th write select circuit first transistor 312 a[n] and [n]th writeselect circuit second transistor 312 b[n] can be a drain, and a draincan be a source. In examples, [n]th write select circuit firsttransistor 312 a[n] and [n]th write select circuit second transistor 312b[n] are also referred to as existing transistors.

I/O block 302 further includes a [n]th write select circuit firstadditional transistor 314 a[n] and a [n]th write select circuit secondadditional transistor 314 b[n]. A source of [n]th write select circuitfirst transistor 312 a[n] is connected to [n]th additional bit lineHBL[n] 210 a[n] and a source of [n]th write select circuit secondadditional transistor 314 b[n] is connected to [n]th complementaryadditional bit line HBLB[n] 210 b[n]. A drain of each of [n]th writeselect circuit first additional transistor 314 a[n] and [n]th writeselect circuit second additional transistor 314 b[n] is connected toground. Moreover, a gate of [n]th write select circuit first transistor312 a[n] is connected to a gate of [n]th write select circuit firstadditional transistor 314 a[n]. In addition, a gate of [n]th writeselect circuit second transistor 312 b[n] is connected to a gate of[n]th write select circuit second additional transistor 314 b[n].

In example embodiments, each of [n]th write select circuit firstadditional transistor 314 a[n] and [n]th write select circuit secondadditional transistor 314 b[n] is a nMOS transistor. However, othertypes of transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,each of [n]th write select circuit first additional transistor 314 a[n]and [n]th write select circuit second additional transistor 314 b[n],are symmetrical. Hence, a source of each of [n]th write select circuitfirst additional transistor 314 a[n] and [n]th write select circuitsecond additional transistor 314 b[n] can be a drain, and a drain can bea source. In examples, [n]th write select circuit first additionaltransistor 314 a[n] and [n]th write select circuit second additionaltransistor 314 b[n] are smaller in size than [n]th write select circuitfirst transistor 312 a[n] and [n]th write select circuit secondtransistor 312 b[n] (that is, the existing transistors).

I/O block 302 further includes a [n]th write select first logic circuit316 a[n] and a [n]th write select second logic circuit 316 b[n]. Each of[n]th write select first logic circuit 316 a[n] and [n]th write selectsecond logic circuit 316 b[n] includes a NOR logic gate. However, othertypes of logic circuits are within the scope of the disclosure.

A first input terminal of [n]th write select first logic circuit 316a[n] is connected to data input true (DT) terminal and a second inputterminal of [n]th write select first logic circuit 316 a[n] is connectedto a [n]th write select bit WYB[n] terminal. An output terminal of [n]thwrite select first logic circuit 316 a[n] is connected to a gate of eachof [n]th write select circuit first transistor 312 a[n] and [n]th writeselect circuit first additional transistor 314 a[n].

A first input terminal of [n]th write select second logic circuit 316b[n] is connected to data input bar (DB) terminal and a second inputterminal of [n]th write select second logic circuit 316 b[n] isconnected to [n]th write select bit WYB[n] terminal. An output terminalof [n]th write select second logic circuit 316 b[n] is connected to agate of each of [n]th write select circuit second transistor 312 b[n]and [n]th write select circuit second additional transistor 314 b[n]. Inexample embodiments, when the [n]th write select bit WYB[n] is at alogic low, a write operation is selected by both [n]th write selectfirst logic circuit 316 a[n] and [n]th write select second logic circuit316 b[n]. However, when the [n]th write select bit WYB[n] is at a logichigh, a write operation is not selected by any of [n]th write selectfirst logic circuit 316 a[n] and [n]th write select second logic circuit316 b[n]. In addition, when the write operation is selected, and whenthe data input true (DT) terminal is at a logic high, a bit value of 1is written in cell array 104. Moreover, when the write operation isselected, and when the data input true (DT) terminal is at a logic low,a bit value of 0 is written in cell array 104.

I/O circuit 302 further includes a [n]th read select circuit firsttransistor 318 a[n] and a [n]th read select circuit second transistor318 b[n]. A source of [n]th read select circuit first transistor 318a[n] is connected to a drain of [n]th pre-charge circuit firsttransistor 304 a[n] which is connected to [n]th bit line LBL[n] 208a[n]. In addition, a source of [n]th read select circuit secondtransistor 318 b[n] is connected to a drain of [n]th pre-charge circuitsecond transistor 304 b[n] which is connected to [n]th complementary bitline LBLB[n] 208 b[n]. A drain of [n]th read select circuit firstadditional transistor 318 a[n] is connected to a data line DL terminaland a drain of [n]th read select circuit second transistor 318 b[n] isconnected to a data line bar DLB terminal. The data line DL and the dataline bar DLB terminal are used for reading data from cell array 104.

Moreover, a gate of [n]th read select circuit first transistor 318 a[n]is connected to a gate of [n]th read select circuit second transistor318 b[n] which in turn is connected to a [n]th read select bit RYB[n]terminal. In example embodiments, when the [n]th read select bit RYB[n]is at a logic low, a read operation is selected. However, when the [n]thread select bit RYB[n] is at a logic high, a read operation is notselected.

In example embodiments, each of [n]th read select circuit firsttransistor 318 a[n] and [n]th read select circuit second transistor 318b[n] is a pMOS transistor. However, other types of transistors, forexample, a MOSFET, a nMOS transistor, a CMOS transistor, etc., arewithin the scope of the disclosure. In addition, each of [n]th readselect circuit first transistor 318 a[n] and [n]th read select circuitsecond transistor 318 b[n], are symmetrical. Hence, a source of each of[n]th read select circuit first transistor 318 a[n] and [n]th readselect circuit second transistor 318 b[n] can be a drain, and a draincan be a source.

FIG. 4 illustrates memory device 100 with a negative voltage generatorcircuit 402 in accordance with some embodiments. Negative voltagegenerator circuit 402 of memory device 100 includes a negative voltagegenerator input terminal 404 and a negative generator output terminal406. Negative voltage generator input terminal 404 is operative toreceive a write assist signal (represented as NBL_ENB). Negative voltagegenerator output terminal 406 is operative to provide a negative voltage(also referred to as NVSS) which is applied to first node 214 to lowerthe Vccmin for a write operation. For example, the negative voltage isprovided at negative voltage generator output terminal 406 which isconnected to the plurality of bit line pairs and the plurality ofadditional bit line pairs.

As shown in FIG. 4, negative voltage generator circuit 402 includes anegative voltage generator first logic gate 408, a negative voltagegenerator second logic gate 410, a negative voltage generator capacitor412, and a negative voltage generator transistor 414. An input ofnegative voltage generator first logic gate 408 is connected to negativevoltage generator input terminal 404. An output of negative voltagegenerator first logic gate 406 is connected to an input of negativevoltage generator second logic gate 408. Thus, negative voltagegenerator first logic gate 406 provides an inverse of the write assistsignal to the input of negative voltage generator second logic gate 408.Negative voltage generator second logic gate 408 is operative to providean inverse of an inverted write assist signal as an output. Therefore,negative voltage generator first logic gate 406 and negative voltagegenerator second logic gate 408 in combination form a delay circuit. Theoutput of negative voltage generator second logic gate 408 is connectedto a first terminal of negative voltage generator capacitor 412. Asecond terminal of negative voltage generator capacitor 412 is connectedto negative voltage generator output terminal 406.

A source of negative voltage generator transistor 414 is connected tonegative voltage generator output terminal 406. A drain of negativevoltage generator transistor 414 is connected to ground. A gate ofnegative voltage generator transistor 414 is connected to negativevoltage generator input terminal 404. In example embodiment, negativevoltage generator transistor 414 is symmetrical, thus, the source can beselected to be the drain while the drain can be selected to be thesource. Moreover, although negative voltage generator transistor 414 isshown to be an nMOS transistor, other types of transistors are withinthe scope of the disclosure. For example, negative voltage generatortransistor 414 may be a MOSFET, a pMOS transistor, and a CMOStransistor.

Generally, a write operation in memory device 100 is triggered by awrite enable signal. That is, the write operation is triggered when thewrite enable changes from a first logic value to a second logic value(for example, from a logic value low to a logic value high, or viceversa. The write assist signal can be generated from the write enablesignal. For example, in some examples, the write assist signal may belinked with the write enable signal and be responsive to the writeenable signal. A write assist signal generator circuit (not shown) maybe provided to generate the write assist signal. For example, when thewrite enable signal changes to a logic high indicating initiation of thewrite operation, the write assist signal may also change to a logic lowenabling negative voltage generator circuit 104. In addition, when thewrite enable signal changes to a logic low indicating an end of thewrite operation, the write assist signal may change to a logic lowdisabling negative voltage generator circuit 402.

During a write operation, when the write assist signal is at a logichigh, the gate of negative voltage generator transistor 414 is also at alogic high, which switches negative voltage generator transistor 414 ONwhich results in charging of negative voltage generator capacitor 412.In this configuration, negative voltage generator circuit 402 is labeledas not enabled or disabled. However, when the write assist signalchanges to a logic low, the gate of negative voltage generatortransistor 414 is also at a logic low, which switches negative voltagegenerator transistor 414 OFF. This causes a discharge from negativevoltage generator capacitor 412, which drives a voltage at negativevoltage generator output terminal 406 to a negative value. This negativevoltage is provided to the bit line BL, which provides a boost for thewrite operation performed to bit cells coupled to the bit line BL. Inthis configuration, negative voltage generator circuit 402 is labeled asenabled.

FIG. 5 illustrates memory device 100 with a plurality of equalizerswitches in accordance with some embodiments. In examples, one equalizerswitch is provided for each column of cell array 104. For example, asshown in FIG. 5, cell array 102 of memory device 100 includes a [n−1]thequalizer switch 502[n−1] and a [n]th equalizer switch 502[n]. Each of[n−1]th equalizer switch 502[n−1] and [n]th equalizer switch 502[n] is atransistor, for example, a pMOS transistor. However other types oftransistors are within scope of the disclosure. For example, each of[n−1]th equalizer switch 502[n−1] and a [n]th equalizer switch 502[n]can be a MOSFET, a nMOS transistor, and a CMOS transistor.

A source of [n−1]th equalizer switch 502[n−1] is connected to [n−1]thbit line LBL[n−1] 508 a[n−1]. A drain of [n−1]th equalizer switch502[n−1] is connected to [n−1]th complementary bit line LBLB[n−1] 508b[n−1]. In example embodiments, [n−1]th equalizer switch 502[n−1] issymmetrical, hence, the source can be selected to be the drain and thedrain can be selected to be the source.

In addition, a source of [n]th equalizer switch 502[n] is connected to[n]th bit line LBL[n] 508 a[n]. A drain of [n]th equalizer switch 502[n]is connected to [n]th complementary bit line LBLB[n] 508 b[n]. Inexample embodiments, [n]th equalizer switch 502[n] is also symmetrical,hence, the source can be selected to be the drain and the drain can beselected to be the source.

A gate of each of [n−1]th equalizer switch 502[n−1] and [n]th equalizerswitch 502[n] is connected to an equalizer driver 504 via equalizer barEQB terminal 506. Equalizer driver 504 is operative to control aswitching of each of [n−1]th equalizer switch 502[n−1] and [n]thequalizer switch 502[n]. For example, equalizer driver 504 chargesequalizer bit EQB terminal 506 to a logic high or a logic low. Whenequalizer bit EQB terminal 506 is charged to a logic high, it switchesOFF each of [n−1]th equalizer switch 502[n−1] and [n]th equalizer switch502[n]. By extension, when equalizer bit EQB terminal 506 is charged toa logic low, it switches ON each of [n−1]th equalizer switch 502[n−1]and [n]th equalizer switch 502[n]. In example examples, equalizer bitEQB terminal 506 is same as is connected to pre-charge bar PCB terminal.

When switched ON, an equalizer switch of the plurality of equalizerswitch connects a bit line of the bit line pair with the complementarybit line of the bit line pair thereby accelerating pre-charging of eachof the bit line and the complementary bit line of the bit line pair. Forexample, when switch ON [n−1]th equalizer switch 502[n−1] connects[n−1]th bit line LBL[n−1] 508 a[n−1] to [n−1]th complementary bit lineLBLB[n−1] 508 b[n−1]. By connecting [n−1]th bit line LBL[n−1] 508 a[n−1]to [n−1]th complementary bit line LBLB[n−1] 508 b[n−1], [n−1]thequalizer switch 502[n−1] equalizes a potential of [n−1]th bit lineLBL[n−1] 508 a[n−1] with a potential of [n−1]th complementary bit lineLBLB[n−1] 508 b[n−1]. Similarly, when switch ON [n]th equalizer switch502[n] connects [n]th bit line LBL[n] 508 a[n] to [n]th complementarybit line LBLB[n] 508 b[n]. By connecting [n]th bit line LBL[n] 508 a[n]to [n]th complementary bit line LBLB[n] 508 b[n], [n]th equalizer switch502[n] equalizes a potential of [n]th bit line LBL[n] 508 a[n] with apotential of [n]th complementary bit line LBLB[n] 508 b[n].

FIG. 6 is a diagram illustrating memory 100 in which the additional pairof bit lines are directly driven by write select logic circuits. Asshown in FIG. 6, [n−1]th bit line LBL[n−1] 208 a[n−1] is associated witha [n−1]th write bar WC[n−1] 602 a[n−1] and [n−1]th complementary bitline LBLB[n−1] 208 b[n−1] is associated with a [n−1]th write trueWT[n−1] 602 b[n−1]. In example embodiments, [n−1]th write bar WC[n−1]602 a[n−1]) is driven by [n−1]th write select first logic circuit 316a[n−1]. That is, an output of [n−1]th write select first logic circuit316 a[n−1] is connected to [n−1]th write bar WC[n−1] 602 a[n−1]).Moreover, [n−1]th write bar WC[n−1] 602 a[n−1]) is also connected to agate of a [n−1]th first connection switch 604 a[n−1]. A source of[n−1]th first connection switch 604 a[n−1] is connected to [n−1]th bitline LBL[n−1] 208 a[n−1] and a drain of [n−1]th first connection switch604[n−1] is connected to ground.

Similarly, [n−1]th write true WT[n−1] 602 b[n−1] is driven by [n−1]thwrite select second logic circuit 316 b[n−1]. That is, an output of[n−1]th write select second logic circuit 316 b[n−1] is connected to[n−1]th write true WT[n−1] 602 b[n−1]). Moreover, [n−1]th write trueWT[n−1] 602 b[n−1] is also connected to a gate of a [n−1]th secondconnection switch 604 b[n−1]. A source of [n−1]th second connectionswitch 604 b[n−1] is connected to [n−1]th complementary bit lineLBLB[n−1] 208 b[n−1] and a drain of [n−1]th second connection switch 604b[n−1] is connected to ground.

In example embodiments, each of [n−1]th first connection switch 604a[n−1] and [n−1]th second connection switch 604 a[n−1] is an nMOStransistor. However, other types of transistors, for example, a MOSFET,a pMOS transistor, a CMOS transistor, etc., are within the scope of thedisclosure. In addition, each of [n−1]th first connection switch 604a[n−1] and [n−1]th second connection switch 604 b[n−1] is symmetrical.That is, a source of each of [n−1]th first connection switch 604 a[n−1]and [n−1]th second connection switch 604 b[n−1] can be a drain and adrain can be a source.

In a write operation, when [n−1]th write select bit WYB[n−1] is at alogic low, both [n−1]th write bar WC[n−1] 602 a[n−1]) and [n−1]th writetrue WT[n−1] 602 b[n−1] are selected. In addition, when both [n−1]thwrite bar WC[n−1] 602 a[n−1]) and [n−1]th write true WT[n−1] 602 b[n−1]are at a logic high, both [n−1]th first connection switch 604 a[n−1] and[n−1]th second connection switch 604 a[n−1] are switched ON. During awrite operation, when both [n−1]th write bar WC[n−1] 602 a[n−1]) and[n−1]th write true WT[n−1] 602 b[n−1] are at a logic low, no data iswritten. However, when [n−1]th write bar WC[n−1] 602 a[n−1]) is at alogic high and [n−1]th write true WT[n−1] 602 b[n−1] is at a logic lowat bit value of 0 is written. In addition, when [n−1]th write barWC[n−1] 602 a[n−1]) is at a logic high and [n−1]th write true WT[n−1]602 b[n−1] is at a logic high at bit value of 1 is written.

Continuing with FIG. 6, [n]th bit line LBL[n] 208 a[n] is associatedwith a [n]th write bar WC[n] 602 a[n] and [n]th complementary bit lineLBLB[n] 208 b[n] is associated with a [n]th write true WT[n] 602 b[n].In example embodiments, [n]th write bar WC[n] 602 a[n]) is driven by[n]th write select first logic circuit 316 a[n]. That is, an output of[n]th write select first logic circuit 316 a[n] is connected to [n]thwrite bar WC[n] 602 a[n]). Moreover, [n]th write bar WC[n] 602 a[n]) isalso connected to a gate of a [n]th first connection switch 604 a[n]. Asource of [n]th first connection switch 604 a[n] is connected to [n]thbit line LBL[n] 208 a[n] and a drain of [n]th first connection switch604[n] is connected to ground.

Similarly, [n]th write true WT[n] 602 b[n] is driven by [n]th writeselect second logic circuit 316 b[n]. That is, an output of [n]th writeselect second logic circuit 316 b[n] is connected to [n]th write trueWT[n] 602 b[n]). Moreover, [n]th write true WT[n] 602 b[n] is alsoconnected to a gate of a [n]th second connection switch 604 b[n]. Asource of [n]th second connection switch 604 b[n] is connected to [n]thcomplementary bit line LBLB[n−1] 208 b[n] and a drain of [n]th secondconnection switch 604 b[n] is connected to ground.

In example embodiments, each of [n]th first connection switch 604 a[n]and [n]th second connection switch 604 b[n] is an nMOS transistor.However, other types of transistors, for example, a MOSFET, a pMOStransistor, a CMOS transistor, etc., are within the scope of thedisclosure. In addition, each of [n]th first connection switch 604 a[n]and [n]th second connection switch 604 b[n] is symmetrical. That is, asource of each of [n]th first connection switch 604 a[n] and [n]thsecond connection switch 604 b[n] can be a drain and a drain can be asource.

In a write operation, when [n]th write select bit WYB[n] is at a logiclow, both [n]th write bar WC[n] 602 a[n]) and [n]th write true WT[n] 602b[n] are selected. In addition, when both [n]th write bar WC[n] 602a[n]) and [n]th write true WT[n] 602 b[n] are at a logic high, both[n]th first connection switch 604 a[n] and [n]th second connectionswitch 604 b[n] are switched ON. During a write operation, when both[n]th write bar WC[n] 602 a[n]) and [n]th write true WT[n] 602 b[n] areat a logic low, no data is written. However, when [n]th write bar WC[n]602 a[n]) is at a logic high and [n]th write true WT[n] 602 b[n] is at alogic low at bit value of 0 is written. In addition, when [n]th writebar WC[n] 602 a[n]) is at a logic high and [n]th write true WT[n] 602b[n] is at a logic high at bit value of 1 is written.

In example embodiments, the additional bit line pairs can be providedfor memory devices having multi-port cells. FIG. 7 is a diagramillustrating a memory device 700 which includes a dual port cell 702 inaccordance with some embodiments. As shown in FIG. 7, dual port cell 702of memory device 700 includes a first port (that is, port A) and asecond port (that is, port B). Memory device 700 further includes afirst bit line pair (that is, a first bit line A_LBL 704 a 1 and a firstcomplementary bit line A_LBLB 704 b 1), and a second pair of bit line(that is, a second bit line B_LBL 704 a 2 and a second complementary bitline B_LBLB 704 b 2). First bit line A_LBL 704 a 1 and firstcomplementary bit line A_LBLB 704 b 1 are associated with the port A. Inaddition, second bit line B_LBL 704 a 2 and second complementary bitline B_LBLB 704 b 2 are associated with the port B.

Moreover, memory device 700 includes a first additional bit line pair(that is, a first additional bit line A_HBL 706 a 1 and a firstcomplementary additional bit line A_HBLB 706 b 1) and a secondadditional pair of bit line (that is, a second additional bit line B_HBL706 a 2 and a second complementary additional bit line B_HBLB 706b2).Each of the additional of bit line pairs are connectable to acorresponding bit line pair. For example, the first additional bit linepair is connectable to the first bit line pair and the second additionalbit line pair is connectable to the second bit line pair. The additionalof bit line pairs are connectable to the corresponding bit line pairthrough a plurality of switches. For example, memory device 700 includesa plurality of switches, that is, a first transistor 710 a, a firstadditional transistor 710 b, a second transistor 712 a, and a secondadditional transistor 712 b.

As shown in FIG. 7, a source of first transistor 710 a is connected tofirst bit line 704 a 1 and a drain of first transistor 710 a isconnected to first additional bit line 706 a 1. Similarly, a source offirst additional transistor 710 b is connected to first complementarybit line 704 b 1 and a drain of first additional transistor 710 b isconnected to first additional complementary bit line 706 b 1. A gate ofeach of first transistor 710 a and first additional transistor 710 b isconnected to a first write enable line A_WEL 708 a.

In example embodiments, each of first transistor 710 a and firstadditional transistor 710 b is an nMOS transistor. However, other typesof transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,each of first transistor 710 a and first additional transistor 710 b issymmetrical. That is, a source of each of first transistor 710 a andfirst additional transistor 710 b can be a drain and a drain can be asource.

In example embodiments, each of first transistor 710 a and firstadditional transistor 710 b are switched ON and switched OFF when firstwrite enable line A_WEL 708 a is at a logic high and a logic lowrespectively. Hence, when first word enable line A_WEL 708 a is at alogic high, first transistor 710 a is switched ON and first bit line 704a 1 is connected to first additional bit line 706 a 1. In addition, whenfirst word enable line A_WEL 708 a is at a logic high, first additionaltransistor 710 b is switched ON and first additional bit line 704 b 1 isconnected to first additional complementary bit line 706 b 1.

When first word enable line A_WEL 708 a is at a logic low, firsttransistor 710 a is switched OFF and first bit line 704 a 1 is notconnected to (or disconnected from) first additional bit line 706 a 1.Moreover, when first word enable line A WEL 708 a is at a logic low,first additional transistor 710 b is switched OFF and first additionalbit line 704 b 1 is not connected to (or disconnected from) firstadditional complementary bit line 706 b 1. In example embodiments, firstword enable line A_WEL 708 a is at a logic high during a write operationand first word enable line A_WEL 708 a is at a logic low during a readoperation.

Continuing with FIG. 7, a source of second transistor 712 a is connectedto second bit line 704 a 2 and a drain of second transistor 712 a isconnected to second additional bit line 706 a 2. Similarly, a source ofsecond additional transistor 712 b is connected to second complementarybit line 704 b 2 and a drain of second additional transistor 712 b isconnected to second additional complementary bit line 706 b 2. A gate ofeach of second transistor 712 a and first additional transistor 712 b isconnected to a second write enable line B_WEL 708 b.

In example embodiments, each of second transistor 712 a and secondadditional transistor 712 b is an nMOS transistor. However, other typesof transistors, for example, a MOSFET, a pMOS transistor, a CMOStransistor, etc., are within the scope of the disclosure. In addition,each of second transistor 712 a and second additional transistor 712 bis symmetrical. That is, a source of each of second transistor 712 a andsecond additional transistor 712 b can be a drain and a drain can be asource.

In example embodiments, each of second transistor 712 a and secondadditional transistor 712 b are switched ON and switched OFF when secondwrite enable line B_WEL 708 b is at a logic high and a logic lowrespectively. For example, when second word enable line B_WEL 708 b isat a logic high, second transistor 712 a is switched ON and second bitline 704 a 2 is connected to second additional bit line 706 a 2. Inaddition, when second write enable line B_WEL 708B is at a logic high,second additional transistor 712 b is switched ON and second additionalbit line 704 b 2 is connected to second additional complementary bitline 706 b 2.

However, when second word enable line B_WEL 708 b is at a logic low,second transistor 712 a is switched OFF and second bit line 704 a 2 isnot connected to (or disconnected from) second additional bit line 706 a2. Moreover, when second word enable line B_WEL 708 b is at a logic low,second additional transistor 712 b is switched OFF and second additionalbit line 704 b 2 is not connected to (or disconnected from) secondadditional complementary bit line 706 b 2. In example embodiments,second word enable line B_WEL 708 b is at a logic high during a writeoperation and second word enable line B_WEL 708 b is at a logic lowduring a read operation. Hence, the additional bit line pairs areconnected to corresponding existing bit line pairs during a writeoperation.

FIG. 8 illustrates steps of a method 800 for operating a memory device.The steps of method 800 may be executed to operate memory devicesdiscussed with reference to FIGS. 1-7 of the disclosure. In exampleembodiments, the steps of method 800 may be performed using logicdevices and formed elements. In addition, the steps of method 800 canalso be performed using a processor and a memory. For example, the stepsof method 800 are stored as instructions on a computer readable mediumwhich when executed by the processor configures the processor to performthe steps of method 800. The computer readable medium can be anon-transitory computer readable medium.

At block 810 of method 800, a write enable signal is received. The writeenable signal is received for writing data in memory device 100. Memorydevice 100 includes a plurality of memory cells arranged in a matrix ofa plurality of rows and a plurality of columns. Each of the plurality ofcolumns include a first plurality of memory cells of the plurality ofmemory cells, and each of the plurality of rows includes a secondplurality of memory cells of the plurality of memory cells.

At block 820 of method 800, a first column of the memory device 100 isselected in response to receiving the write enable signal. For example,[n−1]th column 204 of memory device 100 is selected in response to thewrite enable signal. In other examples, [n]th column 206 of memorydevice 100 is selected in response to the write enable signal.

At block 830 of method 800, a first bit line pair associated with thefirst column is pre-charged. For example, if [n−1]th column 204 isselected, then [n−1]th bit line LBL[n−1] 208 a[n−1] and [n−1]thcomplementary bit line LBLB[n−1] 208 b[n−1] are pre-charged to apre-determined potential. If [n]th column 206 is selected, then [n]thbit line LBL[n] 208 a[n] and [n]th complementary bit line LBLB[n] 208b[n] are pre-charged to a pre-determined potential.

At block 840 of method 800, a second bit line pair associated the firstbit line pair are connected to the first bit line pair. The second bitline pair is connectable to the first bit line pair through a pluralityof switches. For example, [n−1]th additional bit line HBL[n−1] 210a[n−1] and [n−1]th additional complementary bit line HBLB[n−1] 210b[n−1] are connected to [n−1]th bit line LBL[n−1] 208 a[n−1] and [n−1]thcomplementary bit line LBLB[n−1] 208 b[n−1] respectively. For example,[n−1]th additional bit line HBL[n−1] 210 a[n−1] is connected to [n−1]thbit line LBL[n−1] 208 a[n−1] through [n−1]th first switch 212 a 0[n−1]and [n−1]th second switch 212 a 1[n−1]. Moreover, [n−1]th additionalcomplementary bit line HBLB[n−1] 210 b[n−1] is connected to [n−1]thcomplementary bit line LBLB[n−1] 208 b[n−1] through [n−1]th firstcomplementary switch 212 b 0[n−1] and [n−1]th second complementaryswitch 212 b 1[n−1].

In accordance with example embodiments, a memory device comprises: aplurality of memory cells arranged in a matrix of a plurality of rowsand a plurality of columns, wherein a first column of the plurality ofcolumns of the matrix comprises: a first plurality of memory cells ofthe plurality of memory cells, a first pair of bit lines connected toeach of the first plurality of bit cells, and a second pair of bit linesconnectable to the first pair of bit lines through a plurality ofswitches.

In accordance with example embodiments, a memory device comprises: aplurality of memory cells arranged in a matrix of a plurality of rowsand a plurality of columns, wherein each of the plurality of columnscomprises a first plurality of memory cells of the plurality of memorycells, and wherein each of the plurality of rows comprises a secondplurality of memory cells of the plurality of memory cells; a pluralityof first bit line pairs, wherein each first bit line pair of theplurality of first bit line pairs is connected to the first plurality ofmemory cells of a column of the plurality of columns; and a plurality ofsecond bit line pairs, wherein each second bit line pair of theplurality of second bit line pairs is associated with a first bit linepair of the first plurality of bit line pairs, and wherein the eachsecond bit line pair is connectable to the associated first bit linepair through a plurality of switches.

In accordance with example embodiments a method for operating a memorydevice comprises: receiving a write enable signal for writing data in amemory device; selecting, in response to receiving the write enablesignal, a first column of the memory device; pre-charging a first bitline pair associated with the first column; and connecting a second bitline pair associated the first bit line pair to the first bit line pair,wherein the second bit line pair is connectable to the first bit linepair through a plurality of switches.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A memory device comprising: a plurality of memorycells arranged in a matrix of a plurality of rows and a plurality ofcolumns, wherein a first column of the plurality of columns of thematrix comprises: a first plurality of memory cells of the plurality ofmemory cells, a first pair of bit lines connected to each of the firstplurality of bit cells, and a second pair of bit lines connectable tothe first pair of bit lines through a plurality of switches.
 2. Thememory device of claim 1, wherein the first pair of bit lines comprisesa first bit line and a first complementary bit line, wherein the secondpair of bit lines comprises a second bit line and a second complementarybit line, wherein the first bit line is connectable to the second bitline, and wherein the first complementary bit line is connectable to thesecond complementary bit line.
 3. The memory device of claim 2, whereinthe first bit line is connectable to the second bit line through atleast one first switch, and wherein the first complementary bit line isconnectable to the second complementary bit line through at least onesecond switch.
 4. The memory device of claim 3, wherein each of the atleast one first switch and the at least one second switch is switched ONduring a write operation using a write enable signal.
 5. The memorydevice of claim 2, wherein the first bit line is connectable to thesecond bit line through at a first switch after each predeterminednumber of rows, and wherein the first complementary bit line isconnectable to the second complementary bit line through a second switchafter the each predetermined number of rows.
 6. The memory device ofclaim 5, wherein the first switch and the second switch share a writeenable signal to switch it ON.
 7. The memory device of claim 1, whereinthe first pair of bit lines are formed in a first metal layer and thesecond pair of bit lines are formed in a second metal layer, wherein thesecond metal layer is different from the first metal layer.
 8. Thememory device of claim 1, wherein the first pair of bit lines are formedin a first metal layer and the second pair of bit lines are formed in asecond metal layer, wherein the second metal layer is a higher metallayer than the first metal layer.
 9. The memory device of claim 1,wherein the second metal layer is at least two layer higher than thefirst metal layer.
 10. The memory device of claim 1, further comprisingan equalizer switch, wherein the first pair of bit lines comprises afirst bit line and a first complementary bit line, and wherein theequalizer switch selectively connects the first bit line with the firstcomplementary bit line.
 11. The memory device of claim 1, wherein thefirst pair of bit lines comprises a first bit line and a firstcomplementary bit line, and wherein the first bit line is selectivelyconnectable with the first complementary bit line with an equalizerswitch, and wherein the equalizer switch is provided for everypredetermined number of rows.
 12. The memory device of claim 1, furthercomprising a negative voltage generator, wherein the negative voltagegenerator, when enabled, is operative to provide a negative voltage tothe first pair of bit lines and the second pair of bit lines.
 13. Amemory device comprising: a plurality of memory cells arranged in amatrix of a plurality of rows and a plurality of columns, wherein eachof the plurality of columns comprises a first plurality of memory cellsof the plurality of memory cells; a plurality of first bit line pairs,wherein each first bit line pair of the plurality of first bit linepairs is connected to the first plurality of memory cells of a column ofthe plurality of columns; and a plurality of second bit line pairs,wherein each second bit line pair of the plurality of second bit linepairs is associated with a first bit line pair of the plurality of firstbit line pairs, and wherein the each second bit line pair is connectableto the associated first bit line pair through a plurality of switches.14. The memory device of claim 13, wherein the each first bit line paircomprises a first bit line and a first complementary bit line, andwherein the each second bit line pair comprises a second bit line and asecond complementary bit line, wherein the first bit line is connectableto the second bit line, and wherein the first complementary bit line isconnectable to the second complementary bit line.
 15. The memory deviceof claim 14, wherein the first bit line is connectable to the second bitline through at least one first switch, and wherein the firstcomplementary bit line is connectable to the second complementary bitline through at least one second switch.
 16. The memory device of claim15, wherein the at least one first switch and the at least one secondswitch is n-channel metal oxide semiconductor (nMOS) transistor.
 17. Thememory device of claim 14, wherein the first bit line is connectable tothe first complementary bit line through at least one equalizer switch.18. The memory device of claim 17, wherein the at least one equalizerswitch is p-channel metal oxide semiconductor (pMOS) transistor.
 19. Amethod for operating a memory device, the method comprising: receiving awrite enable signal for writing data in a memory device; selecting, inresponse to receiving the write enable signal, a first column of thememory device; pre-charging a first bit line pair associated with thefirst column; and connecting a second bit line pair associated the firstbit line pair to the first bit line pair, wherein the second bit linepair is connectable to the first bit line pair through a plurality ofswitches.
 20. The method of claim 19, wherein the first pair of bitlines comprises a first bit line and a first complementary bit line,wherein the second pair of bit lines comprises a second bit line and asecond complementary bit line, and wherein connecting the second bitline pair associated the first bit line pair to the first bit line pair,comprises: connecting the first bit line to the second bit line, andconnecting the first complementary bit line to the second complementarybit line.